geemus/excon — pull request #301 by burns (2013-10-24 17:55:05+00:00)
Title: remove datum param from valid keys methods

These methods will eventually look something like
```rb
def valid_connection_keys(params = {})
datum = @data || {}
middlewares = params[:middlewares] || datum[:middlewares] || []
Excon::VALID_CONNECTION_KEYS | middlewares.map {|m| m.valid_connection_keys }.flatten
end
```
Although, I'm still considering whether or not middlewares should be able to make keys invalid as well.